Rechargeable batteries such as batteries made up of many lithium-ion cells can be used in many applications, including for example in electric vehicle (“EV”) and hybrid electric vehicle (“HEV”) applications. During charging and discharging, such batteries can generate large amounts of heat that needs to be dissipated.
In advanced battery thermal management systems, individual battery cells are sandwiched between liquid-cooled heat exchanger panels having coolant circulation passages. The amount of heat removed from the cell is related to the flow rate of coolant through the plate. However, as the flow rate increases, the pressure drop also increases, thereby limiting the coolant flow rate and the cooling capacity of the panel.
In addition, most heat exchanger panels are designed to provide a uniform coolant distribution across the surfaces of the panel. However, the heat generated by a lithium-ion battery cell is not uniformly distributed across its surfaces. For example, hot spots may develop at the battery tabs and in the area near the battery tabs, particularly during fast charging of the battery cell, since the tabs of lithium-ion battery cells tend to develop more heat than the rest of the battery cell. In addition, hot spots may develop in the central area of the battery cell during discharge of the battery cell, under drive cycle conditions. Therefore, the cooling of such a battery with panels designed for uniform coolant distribution can result in uneven cooling of the battery cells, resulting in the creation of “hot spots” which can have adverse impacts on battery performance and battery life. Therefore, the removal of excess heat, whether from the area near the battery tabs or other areas of the battery cell, would enhance battery performance and life.
There is a need for a improved constructions of heat exchangers for rechargeable batteries while improving manufacturability, which provide lower pressure drop and/or uniform cooling.